Ethereal-wave-responsive device.



E. WEINTRAUB. ETHEREAL WAVE RESPONSIVE DEVICE. APPLICATION FILED 00127, 1909. RENEWED NOV. 9, 1912.

1 09 142 Patented May 12, 1914.

WL'ZJVESSES' INYENTUR M Z'EE'HIE'L WEINTRAUB. fi i gw QM B75 ATIURAZEK EZECHIEL WEINTRAUB, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ETHEREAL-WAVE-RESI'ONSIVE DEVICE.

Specification of Letters Patent.

Patented May 12, data.

Application filed October 27, 1909, Serial No. 524,946. Renewed November 9, 1912. Serial No. 730,497.

To all EL-ltOl/t it may concern:

Be itknown that I, EZEUIIIEL IVEINTRAUB, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Ethereal lVave Responsive Devices, of which the following is a specification.

My present invention comprises an improved means for detecting and indicating ethereal vibrations, such as those used in the art of wireless signaling, or in bolometric measurements and determination.

Of the wave-detecting devices used for wireless telegraphy and telephony, some are based on the changes of resistance indicated by a conductor when heated by the high frequency waves received from the antenna of the station. Others owve their wave-detecting power to a change in the electrical act-ion of a loose contact between two dissimilar conductive elements. In some cases advantage is taken of the rectifying action and the generation of a thermal electromotive force at the junction between suitable materials. In the Langley bolometer the waves emanating from a light-giving source change the temperature of the receiving element, thereby changing its resistance, and, through the instrumentality of asuitable indicating instrument, giving information concerning the temperature of the source of light.

My present invention embraces an improvement in the various types of wave-detecting instruments'above mentioned, by the use of boron or a boron alloy for at least one of the wave-responding elements of the device.

In the accompanying drawing, Figure 1 indicates diagrammatically a system of connections in which a boron conductor gives indications in a telephone because of its change in resistance when heated by energy received over the antennae; Fig. 2 is a similar diagram, showing a receiver based primarily on the use of a limited contact between the two active elements; Fig. 3 shows how the electromotive force at the junction between two elements can be used to indicate conditions on the, antenna.

Many of the standard textbooks refer to the production of magnesium-borid by reduction of boric anhydrid with magnesium, but prior to my own work in this field, Moissan is the only experimenter of recognized reputation who even claims to have produced pure boron. Moissan sought to prevent the retention of magnesium in the final product by using an excess of the boric anhydrid. He described the product as analyzing )3 to 95 per cent. boron, and as being a brownish powder, practically nonconductive for electricity and vaporizable without fusion. I am convinced that this material was not relatively pure boron, as Moissan supposed, but was in fact a boron suboxid associated with more or less magnesium borid.

I have discovered that elemental boron possesses properties which are altogether clifferent from those possessed by the so-called boron referred to above. Pure or elemental boron can be fused into a dense body, which is black in color and has a conchoidal fracture. It is a fair conductor of electricity, and has a negative temperature resistance co-efiicient of a magnitude without precedent among the chemical elements. I have found that at ordinary room temperatures the conductivity of pure boron doubles approxture. In changing from room temperature imately for 17 degrees increase of temperato tOO degrees 0., it changes according to the ratio of about one to two million. I have also found that the action of boron as a thermo-electric generating element is relatively strong. Claims on the boron thermocouple have been made in Patent N 0. 1,079,621 of November 25, 1913.

The valuable properties of high resistance and the enormous resistance change can be varied within certain limits, so as to adaptthem best to practical requirements, by associating with boron small amounts of other elements, such as silicon, magnesium, aluminium and especially carbon. The initial resistance is then lowered, and the negative temperature resistance coeflicient is also somewhat reduced, depending upon the amount of carbon adde For a full disclosure of my invention, I will first describe some methods for making pure fused boron. According to one process, boron chlorid is reduced with hydrogen in a high voltage alternating current arc maintained between water cooled copper eleo-. trodes, as fully disclosed by me in my Patent No. 1,046,043. During the process of manufacture some of the reduced boron fuses on the ends of the electrodes and grows into beads or rods. Boron in this form can be applied directly to Wave-detecting instruments. Some of the reduced boron, however,

is thrown out by the are as a powder onthe walls of the arc chamber. This powder is compressed into a stick, and is then fused in a. high potential arc operating in hydrogen, using the stick of boron as an electrode. The process and apparatus for carrying out this fusion by means of the high potential are are fully described by me in my Patent No. 1,019,392. The fused product is used in a wave-detecting instrument.

According to another mode of manufacture, an excess of boric anhydrid is first reduced with magnesium. The resulting product consists of magnesium borid, or boron suboxid, or a mixture of both, according to the temperature at which the reaction is carried on. It can be made to yield fused, substantially pure boron by preheating it in a vacuum furnace to drive out some of the impurities and make it partially conductive, and then heating this stick by making it the electrode for a high potential alternating current are operating in hydrogen at a pressure of about five inches of mercury, or by making it the electrode of a mercury-vapor are. Claims are made on some of the above features in my Patent No. 997 ,879.

If it is desired to associate with the boron a certain amount of carbon or other element, this can be accomplished by one of the following methods: A carbon filament is heated in a mixture of boron chlorid and hydrogen, which results in the deposition of boron on the filament. During this process, especially if 'the temperature is raised considerably, the carbon diffuses through the mass of boron. If a perfectly homogeneous product is desired, the mass is fused in a high potential, or mercury arc. As it is possible to use a carbon fillet possessing very small mass, the percentage of carbon can be made practically as small as desired by this method. If higher percentages of carbon are desired, a gaseous carbon compound, such "as vaporized gasolene or carbon tetrachlorid, is added to the mixture of boron chlorid and hydrogen, which results in the deposition of carbon simultaneously with the deposition, of boron. These steps are disclosed'in my Patent No. 1,019,393.. By varying the amount of vapor of the carbon compound in the mixture, the carbon content may'be varied 'atwilL When the addition I of carbon' amounts to as much as 20 per cent, the temperature coefiicient of the product is of the'same general magnitude as that :5 of pur'e'carbon, or, in other words, very much less than that of pure boron. In Fig. 1, I have shown a grounded antenna 1 equipped with the usual local circuit, including a condenser 52, an inductance 3, a local battery 4, and a telephone or other indicating instrument 5 all con nected in series, as indicated in the drawing.

In shunt with a part of this local circuit is a boron element 6, of suitably small cross section, and serving as a wave-responsive device for the local circuit, Energy received over the antenna 1 will be transferred to the boron conductor 6, and there converted into heat, which will so change the conductivity of the boron as to vary the current applied to receiver 5 by the local battery 4. For this purpose a boron element possesses the very important requisites of high initial resistance combined with an enormous temperature resistance coefficient. The battery 1 should be of such low voltage that the boron element will iadiate heat with sufficient rapidity so as not to run away, but will resume its high resistance as soon as the high potential oscillations have passed. In some cases the battery 4 can be entirely dispensed with, the energy for operating the indicating instrument 5 being part of the energy received by the antenna.

Although I have shown the use of an antenna and other conductive elements for applying the vibratory energy to the boron element, it will be apparent that the energy might be initially in the form of light or heat when applied directly to the boron element, according to the general methods made public by Professor Langley and others in their many publications concerning the instrument known as a bolometer.

In Fig. 2, the boron element 7 makes but limited contact with the copper block 8. In 7 this case, energy received over the antenna 9 will be transferred through the inductive connection 10, and the usual condenser 11, and will pass through the point of contact between the boron block 7 and the copper block 8, thereby locally heating the boron, and not only bringing into play the enormous negative. temperature coeflicient of the boron, but also establishing a thermo- 110 electromotive force operative to increase the effect of the local battery 12 on the telephone, or other indicator 13. It may be noted that for this purpose, copper and boron are specially adapted for use in contact, as the low chemical aflinity of one for the other greatly lessens the danger of fusion at the point of contact.

In Fig. 3 the local battery is dispensed with, and the wave-detecting action of the boron element 4: is based on the generation of a thermo-"electromotive force between the boron and the conductive element 15 of other suitable material with'which it is in good contact. This electromotiveforce serves to establishthe flow of current through the path, including an inductance 16, and a galvanometer, or other suitable indicating instrument 17. I

The embodiments above described will mosses serve to indicate the generic character of my present invention, but I desire that they shall be considered as merely illustrative and by no means exhausting the possibilities arising from my discoveries in connection with pure fused boron.

I am aware that boron can with advantage be substituted for other material as the r 2. A wave-responsive element composed mainly of boron and small amounts of other elements. 7

3. A wave-responslve element, comprising essentially fused conductive boron, associated with a small amount of a more conductlve material.

[SEAL] 1. A wave-responsive device composed essentially of boron and small amounts of carbon.

5. A receiver for radiant energy comprising two'conductive elements, one at least of which is composed essentially of boron.

6. A. receiver for radiant energy c0mprising tyvo conductive elements, one of which consists essentially of boron and the other of which is copper.

7. In a Wave-responsive device, a copper block making limited contact with a block consisting largely of uncombined conductive" boron.

8. In a system of signaling by electromagnetic waves, a receiver comprising a thermo-couple having an element consisting largely of boron. 1

In Witness whereof, I have hereunto set my hand this 26th day of October, 1909. EZECHIEL WEINl BAUB. Witnesses:

JOHN A. MGMANUS, Jr., CHARLES A. BARNARD.

It is hereby certified that in Letters Patent No. 1,096,1et2, granted -May 12, 1914, upon the application of Ezechiel Weintraub, of Lynn, Massachusetts, for an improvement in 'Ethereal-Wave-Responsive Devices, an error appears in the printed specification requiring correction as follows: Page 1, transpose lines 81 and 82; and that the said Letters Patent should be read with this correction therein that the same may conform to the recordof the case in the Patent Oflice.

Signed and sealed this 16th day of June, A. D. 1914.

J. T. NEWTON,

Acting Commissioner of Patents. 

